1. Field of the Invention
The present invention relates generally to three-dimensional modeling systems based on boundary representations, and in particular, to a method, apparatus, and article of manufacture for the controlled dragging of faces in boundary representations and solid bodies.
2. Description of the Related Art
The use of solid modeling application programs is well known in the art. In a 3D solid modeling system, a 3D model (also referred to as an object model) may be constructed, displayed, modified, etc. A solid model may be presented to the user by displaying the boundary of the model (referred to as a boundary representation or B-rep). Further, the boundary representation has multiple individual faces. To manipulate/modify the model, a face of the boundary representation may be dragged/repositioned using a cursor control device such as a mouse. However, when a single face is dragged, adjacent faces (i.e., faces that share common edges and vertices with the face being dragged) may become invalid. For example, an adjacent face that was originally planar may become non-planar when vertices shared between the dragged face and adjacent face are repositioned (such that the vertices of the adjacent face do not lie on the same plane any more).
Additionally, in prior art solid modeling application programs, the user cannot control how adjacent faces should be adjusted during a face dragging operation. For example, without input from the user, a solid modeling application program may adjust adjacent faces in a predetermined manner during a face dragging operation. Thus, the user is not provided with any option(s) and does not have the capability to control or elect between multiple different types of face dragging operations.
Accordingly, what is needed is a method, system, and article of manufacture for repositioning a face of a boundary representation while providing the user with options to control the repositioning operation.